Water treatment usually involves the use of some form of chlorine. The discharge of chlorinated water from water supply systems, for example from a hydrant of the system, can cause harm to the environment and laws restricting or preventing such discharge are commonplace in the United States and elsewhere.
As a consequence, a number of approaches have been devised in an attempt to dechlorinate water at or prior to discharge. One well known agent for neutralizing chlorine is sodium thiosulfate. It is known to form a solution including such material at a water supply system discharge outlet, for example the outlet of a fire hydrant, and attempt to meter drip or flow of the solution into the water being discharged. This is often ineffective and difficult to monitor and it is virtually impossible to ensure that an appropriate amount of solution is added to the discharge water. Furthermore, crystallization within the solution is a common occurrence and such crystallization interferes with or even prevents application of the solution. In general, regulating the addition of the solution to the flow of water is a difficult and inefficient process.
It is known to form dechlorinating material into tablets which are engaged by the water being discharged. Examples of such tablets are tablets sold by Exceltec under the trademark D-Chlor. It is known to position such tablets in a mat or screen for engagement by the discharged water, however, these approaches are not completely satisfactory in that erosion of the tablets, and thus introduction of the dechlorinating neutralization agent in the water, is very difficult to control. A dangerous situation can be created if inadequate or improper mixing of the dechlorinating agent and discharged water takes place.
The following patents are also considered of some pertinence to the issue of the state of the prior art in this field: U.S. Pat. No. 5,788,858, issued Aug. 4, 1998, U.S. Pat. No. 4,402,531, issued Sep. 6, 1983, U.S. Pat. No. 3,650,471, issued Mar. 21, 1972, U.S. Pat. No. 5,810,044, issued Sep. 22, 1998, U.S. Pat. No. 4,805,862, issued Feb. 21,1989, U.S. Pat. No. 5,350,512, issued Sep. 27, 1994.
None of the patents cited above disclose the invention as described and claimed herein.